This invention relates to the generation of AC power, preferably of sinusoidal waveform, from DC, as is common in the power systems of airborn vehicles. In recent years, power converter systems have been developed which produce sinusoidal AC power by filtering the combined outputs of two or more DC to AC inverters producing flat-topped voltages of varying width and/or phase to produce a stepped sinusoidal-like waveform which can be easily filtered into a near ideal sinusoidal voltage waveform. U.S. Pat. No. 3,579,081 discloses one such converter system found especially useful for this purpose. Generally, the individual DC to AC inverters utilize one or more regulated DC power supplies. Such power supplies sometimes comprise DC to DC inverter circuits to produce DC of the desired value which may be greater than the output of the available DC battery or other DC power source. To maintain the voltage of the AC output of such converter systems under widely varying load conditions or under transient conditions has heretofore proposed problems in the design of such equipment. While various regulating techniques have been satisfactory under various slowly varying or static load conditions, the prior art has left much to be desired from the standpoint of cost and efficiency when the specifications require regulation under transient or other rapidly varying load conditions. The power system of U.S. Pat. No. 3,581,212, represents one attempt to produce a regulated stepped waveform for DC to AC converter systems which is supposed to respond reasonably quickly to rapidly varying load and other conditions.
An object of the present invention is to provide a fast response regulated DC to AC power converter system which is an improvement over that disclosed in U.S. Pat. No. 3,581,212 in that it is a less costly and more efficient regulated power converter system. (The converter circuit disclosed in this patent obtains a desired regulated sinusoidal-like output by continuously switching in and out one or more regulated inverter circuits which supply appreciable proportions of the power of the desired ideal signal under control of circuits which generate ideal upper and lower signal limits and compare the same with a signal derived from the converter circuit output.)